1. Field of the Invention
The present invention relates to a variable logic operation apparatus and, more particularly, it relates to a variable logic operation apparatus for performing logic operation based on a predetermined logic expression which is given from an external stage (for example, a user). In this case, n-nary input data, preferably, binary, ternary, or quaternary are used as operation input data to this apparatus.
2. Description of the Related Art
In a design process of a VLSI (Very Large Scale Integrated) circuit, a logic simulation apparatus is usually used for confirming whether or not a designed logic circuit operates normally in accordance with a specification. Accordingly, it is required that the logic simulation apparatus executes various logic operations at high speed.
There are three kinds of known methods for performing a logic operation, i.e., an operator method, a truth value method, and an FPGA (Field Programmable Gate Array) method.
As explained in detail hereinafter, the main differences among these methods are as follows. That is, in the operator method, each logic (i.e., AND, OR, etc.) of the logic expression is separately processed in a logic operation unit. In the truth value method, the logic expression is processed collectively in the logic operation unit. In the FPGA method, the logic expression is processed by using a programmable logic circuit. There are, however, various problems in these known three methods as explained in detail hereinafter.